A. fall B. seek C. fat D. energy E. makes F. truth G. converted H. argument I. muscles J. rafter K. scarce L. reproduce M. widen N. react O. ecological Some persons say that love 1 the wo r ld go round. Others of a less romantic and more practical turn of mind say that it isn't love; it's money. But the 2 is that it is 3 that makes the world go round. Energy is the currency of the 4 system and life becomes possible only when food is 5 into energy, which in turn is used to 6 more food to grow, to 7 and to survive. On this cycle all life depends. It is fairly well known that wild animals survive from year to year by eating as much as they can during times of plenty, the summer and 8 , storing the excess, usually in the form of 9 , and then using these reserves of fat to survive during the hard times in winter when food is 10 . But it is probably less well known that even with their stored fat, wild animals spend less energy to live in winter than in summer.